<PAGE>

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM 10-K

(Mark One)

|X|  ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE
      ACT OF 1934

For the fiscal year ended                 December 31, 1999
                         -------------------------------------------------------

                                       OR

|_|   TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
      EXCHANGE ACT OF 1934 [NO FEE REQUIRED]

For the transition period from                      to
                              ---------------------    -------------------------

Commission file number                        33-35148-02
                        --------------------------------------------------------

         American Income Fund I-B, a Massachusetts Limited Partnership
--------------------------------------------------------------------------------
             (Exact name of registrant as specified in its charter)

Massachusetts                                   04-3106525
------------------------------------            --------------------------------
(State or other jurisdiction of                 (IRS Employer
incorporation or organization)                  Identification No.)

88 Broad St., Sixth Floor, Boston, MA           02110
----------------------------------------        --------------------------------
(Address of principal executive offices)        (Zip Code)

Registrant's telephone number, including area code         (617) 854-5800
                                                  ------------------------------

Securities registered pursuant to Section 12(b) of the Act        NONE
                                                           ---------------------

  Title of each class               Name of each exchange on which registered

------------------------          ----------------------------------------------
------------------------          ----------------------------------------------

Securities registered pursuant to Section 12(g) of the Act:

             286,711 Units Representing Limited Partnership Interest
--------------------------------------------------------------------------------
                                (Title of class)

--------------------------------------------------------------------------------
                                (Title of class)

      Indicate by check mark whether the registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days. Yes |X| No |_|

      State the aggregate market value of the voting stock held by nonaffiliates
of the registrant. Not applicable. Securities are nonvoting for this purpose.
Refer to Item 12 for further information.

                       DOCUMENTS INCORPORATED BY REFERENCE
       Portions of the Registrant's Annual Report to security holders for
                the year ended December 31, 1999 (Part I and II)
<PAGE>

                            AMERICAN INCOME FUND I-B,
                       a Massachusetts Limited Partnership

                                    FORM 10-K

                                TABLE OF CONTENTS

                                                                            Page
                                                                            ----

                                     PART I

Item 1.     Business                                                           3

Item 2.     Properties                                                         4

Item 3.     Legal Proceedings                                                  4

Item 4.     Submission of Matters to a Vote of Security Holders                4


                                     PART II

Item 5.     Market for the Partnership's Securities and Related Security
            Holder Matters                                                     5

Item 6.     Selected Financial Data                                            6

Item 7.     Management's Discussion and Analysis of Financial Condition
            and Results of Operations                                          6

Item 8.     Financial Statements and Supplementary Data                        6

Item 9.     Changes in and Disagreements with Accountants on Accounting
            and Financial Disclosure                                           6


                                    PART III

Item 10.    Directors and Executive Officers of the Partnership                7

Item 11.    Executive Compensation                                             9

Item 12.    Security Ownership of Certain Beneficial Owners and Management     9

Item 13.    Certain Relationships and Related Transactions                    10


                                     PART IV

Item 14.    Exhibits, Financial Statement Schedules and Reports on
            Form 8-K                                                       12-15


                                       2
<PAGE>

PART I

Item 1. Business.

   (a) General Development of Business

   American Income Fund I-B, a Massachusetts Limited Partnership, (the
"Partnership") was organized as a limited partnership under the Massachusetts
Uniform Limited Partnership Act (the "Uniform Act") on December 31, 1990 for the
purpose of acquiring and leasing to third parties a diversified portfolio of
capital equipment. Partners' capital initially consisted of contributions of
$1,000 from the General Partner (AFG Leasing VI Incorporated) and $100 from the
Initial Limited Partner (AFG Assignor Corporation). On March 1, 1991, the
Partnership issued 286,711 units of limited partnership interest (the "Units")
to 453 investors. The Partnership has one General Partner, AFG Leasing VI
Incorporated, a Massachusetts corporation formed in 1990 and an affiliate of
Equis Financial Group Limited Partnership (formerly known as American Finance
Group), a Massachusetts limited partnership ("EFG" or the "Manager"). The
General Partner is not required to make any other capital contributions except
as may be required under the Uniform Act and Section 6.1(b) of the Amended and
Restated Agreement and Certificate of Limited Partnership (the "Restated
Agreement, as amended").

   (b) Financial Information About Industry Segments

   The Partnership is engaged in only one industry segment: the business of
acquiring capital equipment and leasing the equipment to creditworthy lessees on
a full payout or operating lease basis. Full payout leases are those in which
aggregate undiscounted, noncancellable rents equal or exceed the acquisition
cost of the leased equipment. Operating leases are those in which the aggregate
undiscounted, noncancellable rental payments are less than the acquisition cost
of the leased equipment. Industry segment data is not applicable.

   (c) Narrative Description of Business

   The Partnership was organized to acquire a diversified portfolio of capital
equipment subject to various full payout and operating leases and to lease the
equipment to third parties as income-producing investments. More specifically,
the Partnership's primary investment objectives were to acquire and lease
equipment that would:

   1. Generate quarterly cash distributions;

   2. Preserve and protect Partnership capital; and

   3. Maintain substantial residual value for ultimate sale.

   The Partnership has the additional objective of providing certain federal
income tax benefits.

   The Closing Date of the offering of Units of the Partnership was March 1,
1991. Significant operations commenced coincident with the Partnership's initial
purchase of equipment and the associated lease commitments on March 1, 1991. The
acquisition of the equipment and its associated leases is described in Note 3 to
the financial statements included in Item 14, herein. The Restated Agreement, as
amended, provides that the Partnership will terminate no later than December 31,
2002. However, the Partnership is a Nominal Defendant in a Class Action Lawsuit,
the outcome of which could significantly alter the nature of the Partnership's
organization and its future business operations. See Note 6 to the financial
statements in the 1999 Annual Report.

   The Partnership has no employees; however, it is managed pursuant to a
Management Agreement with EFG or one of its affiliates. The Manager's role,
among other things, is to (i) evaluate, select, negotiate, and consummate the
acquisition of equipment, (ii) manage the leasing, re-leasing, financing, and
refinancing of equipment, and (iii) arrange the resale of equipment. The Manager
is compensated for such services as provided for in the Restated Agreement, as
amended, described in Item 13 herein, and in Note 4 to the financial statements
included in Item 14, herein.

   The Partnership's investment in equipment is, and will continue to be,
subject to various risks, including physical deterioration, technological
obsolescence and defaults by lessees. A principal business risk of owning


                                       3
<PAGE>

and leasing equipment is the possibility that aggregate lease revenue and
equipment sale proceeds will be insufficient to provide an acceptable rate of
return on invested capital after payment of all debt service costs and operating
expenses. In addition, the leasing industry is very competitive. The Partnership
is subject to considerable competition when equipment is re-leased or sold at
the expiration of primary lease terms. The Partnership must compete with lease
programs offered directly by manufacturers and other equipment leasing
companies, including limited partnerships and trusts organized and managed
similarly to the Partnership, and including other EFG-sponsored partnerships and
trusts, which may seek to re-lease or sell equipment within their own portfolios
to the same customers as the Partnership. Many competitors have greater
financial resources and more experience than the Partnership, the General
Partner and the Manager. In addition, default by a lessee under a lease may
cause equipment to be returned to the Partnership at a time when the General
Partner or the Manager is unable to arrange for the re-lease or sale of such
equipment. This could result in the loss of anticipated revenue.

   Revenue from major individual lessees which accounted for 10% or more of
lease revenue during the years ended December 31, 1999, 1998 and 1997 is
incorporated herein by reference to Note 2 to the financial statements in the
1999 Annual Report. Refer to Item 14(a)(3) for lease agreements filed with the
Securities and Exchange Commission.

   EFG is a Massachusetts limited partnership formerly known as American Finance
Group ("AFG"). AFG was established in 1988 as a Massachusetts general
partnership and succeeded American Finance Group, Inc., a Massachusetts
corporation organized in 1980. EFG and its subsidiaries (collectively, the
"Company") are engaged in various aspects of the equipment leasing business,
including EFG's role as Manager or Advisor to the Partnership and several other
direct-participation equipment leasing programs sponsored or co-sponsored by EFG
(the "Other Investment Programs"). The Company arranges to broker or originate
equipment leases, acts as remarketing agent and asset manager, and provides
leasing support services, such as billing, collecting, and asset tracking.

   The general partner of EFG, with a 1% controlling interest, is Equis
Corporation, a Massachusetts corporation owned and controlled entirely by Gary
D. Engle, its President, Chief Executive Officer and sole Director. Equis
Corporation also owns a controlling 1% general partner interest in EFG's 99%
limited partner, GDE Acquisition Limited Partnership ("GDE LP"). Mr. Engle
established Equis Corporation and GDE LP in December 1994 for the sole purpose
of acquiring the business of AFG.

   In January 1996, the Company sold certain assets of AFG relating primarily to
the business of originating new leases, and the name "American Finance Group,"
and its acronym, to a third party. AFG changed its name to Equis Financial Group
Limited Partnership after the sale was concluded. Pursuant to terms of the sale
agreements, EFG specifically reserved the rights to continue using the name
American Finance Group and its acronym in connection with the Partnership and
the Other Investment Programs and to continue managing all assets owned by the
Partnership and the Other Investment Programs.

   (d) Financial Information about Foreign and Domestic Operations and Export
Sales

   Not applicable.

Item 2. Properties.

   Incorporated herein by reference to Note 3 to the financial statements in the
1999 Annual Report.

Item 3. Legal Proceedings.

   Incorporated herein by reference to Note 6 to the financial statements in the
1999 Annual Report.

Item 4. Submission of Matters to a Vote of Security Holders.

   None.


                                       4
<PAGE>

PART II

Item 5. Market for the Partnership's Securities and Related Security Holder
        Matters.

   (a) Market Information

   There is no public market for the resale of the Units and it is not
anticipated that a public market for resale of the Units will develop.

   (b) Approximate Number of Security Holders

   At December 31, 1999, there were 444 record holders in the Partnership.

   (c) Dividend History and Restrictions

   Historically, the amount of cash distributions to be paid to the Partners has
been determined on a quarterly basis. Each quarter's distribution may have
varied in amount and was made 95% to the Limited Partners and 5% to the General
Partner. Generally, cash distributions have been paid within 15 days after the
completion of each calendar quarter.

   The Partnership is a Nominal Defendant in a Class Action Lawsuit described in
Note 6 to the accompanying Annual Report. The proposed settlement to that
lawsuit, if effected, will materially change the future organizational structure
and business interests of the Partnership, as well as its cash distribution
policies. In addition, commencing with the first quarter of 2000, the General
Partner believes that it will be in the Partnership's best interests to suspend
the payment of quarterly cash distributions pending final resolution of the
Class Action Lawsuit. Accordingly, future cash distributions are not expected to
be paid until the Class Action Lawsuit is adjudicated.

   Distributions in 1999 and 1998 were as follows:

                                                     General          Limited
                                     Total           Partner         Partners
                                 -----------      -----------      -----------
Total 1999 distributions         $   226,351      $    11,318      $   215,033

Total 1998 distributions             226,351           11,318          215,033
                                 -----------      -----------      -----------
             Total               $   452,702      $    22,636      $   430,066
                                 ===========      ===========      ===========

   Distributions payable were $56,588 at both December 31, 1999 and 1998.

   There are no formal restrictions under the Restated Agreement, as amended,
that materially limit the Partnership's ability to pay cash distributions,
except that the General Partner may suspend or limit cash distributions to
ensure that the Partnership maintains sufficient working capital reserves to
cover, among other things, operating costs and potential expenditures, such as
refurbishment costs to remarket equipment upon lease expiration. Liquidity is
especially important as the Partnership matures and sells equipment, because the
remaining equipment base consists of fewer revenue-producing assets that are
available to cover prospective cash disbursements. Insufficient liquidity could
inhibit the Partnership's ability to sustain its operations or maximize the
realization of proceeds from remarketing its remaining assets.

   Cash distributions consist of Distributable Cash From Operations and
Distributable Cash From Sales or Refinancings.

   "Distributable Cash From Operations" means the net cash provided by the
Partnership's normal operations after general expenses and current liabilities
of the Partnership are paid, reduced by any reserves for working capital and
contingent liabilities to be funded from such cash, to the extent deemed
reasonable by the General Partner, and increased by any portion of such reserves
deemed by the General Partner not to be required for Partnership operations and
reduced by all accrued and unpaid Equipment Management Fees and, after Payout,


                                       5
<PAGE>

further reduced by all accrued and unpaid Subordinated Remarketing Fees.
Distributable Cash From Operations does not include any Distributable Cash From
Sales or Refinancings.

   "Distributable Cash From Sales or Refinancings" means Cash From Sales or
Refinancings as reduced by (i)(a) amounts realized from any loss or destruction
of equipment which the General Partner determines shall be reinvested in similar
equipment for the remainder of the original lease term of the lost or destroyed
equipment, or in isolated instances, in other equipment, if the General Partner
determines that investment of such proceeds will significantly improve the
diversity of the Partnership's equipment portfolio, and subject in either case
to satisfaction of all existing indebtedness secured by such equipment to the
extent deemed necessary or appropriate by the General Partner, or (b) the
proceeds from the sale of an interest in equipment pursuant to any agreement
governing a joint venture which the General Partner determines will be invested
in additional equipment or interests in equipment and which ultimately are so
reinvested and (ii) any accrued and unpaid Equipment Management Fees and, after
Payout, any accrued and unpaid Subordinated Remarketing Fees.

   "Cash From Sales or Refinancings" means cash received by the Partnership from
sale or refinancing transactions, as reduced by (i)(a) all debts and liabilities
of the Partnership required to be paid as a result of sale or refinancing
transactions, whether or not then due and payable (including any liabilities on
an item of equipment sold which are not assumed by the buyer and any remarketing
fees required to be paid to persons not affiliated with the General Partner, but
not including any Subordinated Remarketing Fees whether or not then due and
payable) and (b) general expenses and current liabilities of the Partnership
(other than any portion of the Equipment Management Fee which is required to be
accrued and the Subordinated Remarketing Fee) and (c) any reserves for working
capital and contingent liabilities funded from such cash to the extent deemed
reasonable by the General Partner and (ii) increased by any portion of such
reserves deemed by the General Partner not to be required for Partnership
operations. In the event the Partnership accepts a note in connection with any
sale or refinancing transaction, all payments subsequently received in cash by
the Partnership with respect to such note shall be included in Cash From Sales
or Refinancings, regardless of the treatment of such payments by the Partnership
for tax or accounting purposes. If the Partnership receives purchase money
obligations in payment for equipment sold, which are secured by liens on such
equipment, the amount of such obligations shall not be included in Cash From
Sales or Refinancings until the obligations are fully satisfied.

   "Payout" is defined as the first time when the aggregate amount of all
distributions to the Limited Partners of Distributable Cash From Operations and
Distributable Cash From Sales or Refinancings equals the aggregate amount of the
Limited Partners' original capital contributions plus a cumulative annual
distribution of 11% (compounded quarterly and calculated beginning with the last
day of the month of the Partnership's Closing Date) on their aggregate
unreturned capital contributions. For purposes of this definition, capital
contributions shall be deemed to have been returned only to the extent that
distributions of cash to the Limited Partners exceed the amount required to
satisfy the cumulative annual distribution of 11% (compounded quarterly) on the
Limited Partners' aggregate unreturned capital contributions, such calculation
to be based on the aggregate unreturned capital contributions outstanding on the
first day of each fiscal quarter.

Item 6. Selected Financial Data.

   Incorporated herein by reference to the section entitled "Selected Financial
Data" in the 1999 Annual Report.

Item 7. Management's Discussion and Analysis of Financial Condition and Results
        of Operations.

   Incorporated herein by reference to the section entitled "Management's
Discussion and Analysis of Financial Condition and Results of Operations" in the
1999 Annual Report.

Item 8. Financial Statements and Supplementary Data.

   Incorporated herein by reference to the financial statements and
supplementary data included in the 1999 Annual Report.

Item 9. Changes in and Disagreements with Accountants on Accounting and
        Financial Disclosure.

   None.


                                       6
<PAGE>

PART III

Item 10. Directors and Executive Officers of the Partnership.

   (a-b) Identification of Directors and Executive Officers

   The Partnership has no Directors or Officers. As indicated in Item 1 of this
report, AFG Leasing VI Incorporated is the sole General Partner of the
Partnership. Under the Restated Agreement, as amended, the General Partner is
solely responsible for the operation of the Partnership's properties. The
Limited Partners have no right to participate in the control of the
Partnership's general operations, but they do have certain voting rights, as
described in Item 12 herein. The names, titles and ages of the Directors and
Executive Officers of the General Partner as of March 15, 2000 are as follows:

DIRECTORS AND EXECUTIVE OFFICERS OF
THE GENERAL PARTNER (See Item 13)

          Name                         Title                   Age       Term
----------------------   -----------------------------------  -----    ---------

Geoffrey A. MacDonald    Chairman and a member of the                   Until a
                         Executive Committee of EFG                    successor
                         and President and a Director                   is duly
                         of the General Partner                51       elected
                                                                          and
                                                                       qualified
Gary D. Engle            President and Chief Executive
                         Officer and member of the
                         Executive Committee of EFG            51

Gary M. Romano           Executive Vice President and Chief
                         Operating Officer of EFG and
                         Clerk of the General Partner          40

James A. Coyne           Executive Vice President of EFG       39

Michael J. Butterfield   Senior Vice President, Finance and
                         Treasurer of EFG and Treasurer of
                         the General Partner                   40

Sandra L. Simonsen       Senior Vice President, Information
                         Systems of EFG                        49

Gail D. Ofgant           Senior Vice President, Lease
                         Operations of EFG                     34

   (c) Identification of Certain Significant Persons

   None.

   (d) Family Relationship

   No family relationship exists among any of the foregoing Partners, Directors
or Executive Officers.


                                       7
<PAGE>

(e) Business Experience

   Mr. MacDonald, age 51, is a co-founder, Chairman and a member of the
Executive Committee of EFG and President and a Director of the General Partner.
Mr. MacDonald was also a co-founder, Director, and Senior Vice President of
EFG's predecessor corporation from 1980 to 1988. Mr. MacDonald is President of
American Finance Group Securities Corp. and a limited partner in Atlantic
Acquisition Limited Partnership ("AALP") and Old North Capital Limited
Partnership ("ONC"). Prior to co-founding EFG's predecessors, Mr. MacDonald held
various executive and management positions in the leasing and pharmaceutical
industries. Mr. MacDonald holds a M.B.A. from Boston College and a B.A. degree
from the University of Massachusetts (Amherst).

   Mr. Engle, age 51, is President and Chief Executive Officer of EFG and sole
shareholder and Director of its general partner, Equis Corporation and a member
of the Executive Committee of EFG and President of AFG Realty Corporation. Mr.
Engle joined EFG in 1990 as Executive Vice President and acquired control of EFG
and its subsidiaries in December 1994. Mr. Engle is Vice President and a
Director of certain of EFG's subsidiaries and affiliates, a limited partner in
AALP and ONC and controls the general partners of AALP and ONC. Mr. Engle is
also Chairman, Chief Executive Officer, and a member of the Board of Directors
of Semele Group, Inc. ("Semele"). From 1987 to 1990, Mr. Engle was a principal
and co-founder of Cobb Partners Development, Inc., a real estate and mortgage
banking company. From 1980 to 1987, Mr. Engle was Senior Vice President and
Chief Financial Officer of Arvida Disney Company, a large-scale community
development company owned by Walt Disney Company. Prior to 1980, Mr. Engle
served in various management consulting and institutional brokerage capacities.
Mr. Engle has a MBA from Harvard University and a BS degree from the University
of Massachusetts (Amherst).

   Mr. Romano, age 40, became Executive Vice President and Chief Operating
Officer of EFG, and Secretary of Equis Corporation in 1996 and is Secretary or
Clerk of several of EFG's subsidiaries and affiliates. Mr. Romano joined EFG in
November 1989, became Vice President and Controller in April 1993 and Chief
Financial Officer in April 1995. Mr. Romano assumed his current position in
April 1996. Mr. Romano is also Vice President and Chief Financial Officer of
Semele. Prior to joining EFG, Mr. Romano was Assistant Controller for a
privately held real estate development and mortgage origination company that he
joined in 1987. Previously, Mr. Romano was an Audit Manager at Ernst & Whinney
(now Ernst & Young LLP), where he was employed from 1982 to 1986. Mr. Romano is
a Certified Public Accountant and holds a B.S. degree from Boston College.

   Mr. Coyne, age 39, is Executive Vice President, Capital Markets of EFG and
President, Chief Operating Officer and a member of the Board of Directors of
Semele. Mr. Coyne joined EFG in 1989, remained until May 1993, and rejoined EFG
in November 1994. In September 1997, Mr. Coyne was appointed Executive Vice
President of EFG. Mr. Coyne is a limited partner in AALP and ONC. From May 1993
through November 1994, he was employed by the Raymond Company, a private
investment firm, where he was responsible for financing corporate and real
estate acquisitions. From 1985 through 1989, Mr. Coyne was affiliated with a
real estate investment company and an equipment leasing company. Prior to 1985,
he was with the accounting firm of Ernst & Whinney (now Ernst & Young LLP). He
has a BS in Business Administration from John Carroll University, a Masters
Degree in Accounting from Case Western Reserve University and is a Certified
Public Accountant.

   Mr. Butterfield, age 40, is Senior Vice President, Finance and Treasurer of
EFG and certain of its affiliates and is Treasurer of the General Partner and
Semele. Mr. Butterfield joined EFG in June 1992, became Vice President, Finance
and Treasurer of EFG and certain of its affiliates in April 1996 and was
promoted to Senior Vice President, Finance and Treasurer of EFG and certain of
its affiliates in July 1998. Prior to joining EFG, Mr. Butterfield was an Audit
Manager with Ernst & Young LLP, which he joined in 1987. Mr. Butterfield was
employed in public accounting and industry positions in New Zealand and London
(UK) prior to coming to the United States in 1987. Mr. Butterfield attained his
Associate Chartered Accountant (A.C.A.) professional qualification in New
Zealand and has completed his CPA requirements in the United States. He holds a
Bachelor of Commerce degree from the University of Otago, Dunedin, New Zealand.

   Ms. Simonsen, age 49, joined EFG in February 1990 and was promoted to Senior
Vice President, Information Systems of EFG in April 1996. Prior to joining EFG,
Ms. Simonsen was Vice President, Information Systems with Investors Mortgage
Insurance Company, which she joined in 1973. Ms. Simonsen provided systems
consulting for a subsidiary of American International Group and authored a
software program published by IBM. Ms. Simonsen holds a BA degree from Wilson
College.


                                       8
<PAGE>

   Ms. Ofgant, age 34, is Senior Vice President, Lease Operations of EFG and
certain of its affiliates. Ms. Ofgant joined EFG in July 1989, was promoted to
Manager Lease Operations in April 1994, and became Vice President of Lease
Operations in April 1996. In July 1998, Ms. Ofgant was promoted to Senior Vice
President of Lease Operations. Prior to joining EFG, Ms. Ofgant was employed by
Security Pacific National Trust Company. Ms. Ofgant holds a BS degree in Finance
from Providence College.

   (f) Involvement in Certain Legal Proceedings

   None.

   (g) Promoters and Control Persons

   See Item 10 (a-b) above.

Item 11. Executive Compensation.

   (a) Cash Compensation

   Currently, the Partnership has no employees. However, under the terms of the
Restated Agreement, as amended, the Partnership is obligated to pay all costs of
personnel employed full or part-time by the Partnership, including officers or
employees of the General Partner or its Affiliates. There is no plan at the
present time to make any officers or employees of the General Partner or its
Affiliates employees of the Partnership. The Partnership has not paid and does
not propose to pay any options, warrants or rights to the officers or employees
of the General Partner or its Affiliates.

   (b) Compensation Pursuant to Plans

   None.

   (c) Other Compensation

   Although the Partnership has no employees, as discussed in Item 11(a),
pursuant to Section 9.4(c) of the Restated Agreement, as amended, the
Partnership incurs a monthly charge for personnel costs of the Manager for
persons engaged in providing administrative services to the Partnership. A
description of the remuneration paid by the Partnership to the Manager for such
services is included in Item 13, herein and in Note 4 to the financial
statements included in Item 14, herein.

   (d) Compensation of Directors

   None.

   (e) Termination of Employment and Change of Control Arrangement

   There exists no remuneration plan or arrangement with the General Partner or
its Affiliates which results or may result from their resignation, retirement or
any other termination.

Item 12. Security Ownership of Certain Beneficial Owners and Management.

   By virtue of its organization as a limited partnership, the Partnership has
outstanding no securities possessing traditional voting rights. However, as
provided in Section 10.2(a) of the Restated Agreement, as amended (subject to
Sections 10.2(b) and 10.3), a majority interest of the Limited Partners has
voting rights with respect to:

      1. Amendment of the Restated Agreement;

      2. Termination of the Partnership;

      3. Removal of the General Partner; and


                                       9
<PAGE>

      4. Approval or disapproval of the sale of all, or substantially all, of
         the assets of the Partnership (except in the orderly liquidation of the
         Partnership upon its termination and dissolution).

   No person or group is known by the General Partner to own beneficially more
than 5% of the Partnership's 286,711 outstanding Units as of March 1, 2000.

   The ownership and organization of EFG is described in Item 1 of this report.

Item 13. Certain Relationships and Related Transactions.

   The General Partner of the Partnership is AFG Leasing VI Incorporated, an
affiliate of EFG.

   (a) Transactions with Management and Others

   All operating expenses incurred by the Partnership are paid by EFG on behalf
of the Partnership and EFG is reimbursed at its actual cost for such
expenditures. Fees and other costs incurred during the years ended December 31,
1999, 1998 and 1997, which were paid or accrued by the Partnership to EFG or its
Affiliates, are as follows:

                                        1999             1998            1997
                                     ----------       ----------      ----------

Equipment management fees            $   10,590       $   13,384      $   28,733
Administrative charges                   85,773           57,048          53,604
Reimbursable operating expenses
   due to third parties                 146,577          393,632          61,100
                                     ----------       ----------      ----------

                    Total            $  242,940       $  464,064      $  143,437
                                     ==========       ==========      ==========

   As provided under the terms of the Management Agreement, EFG is compensated
for its services to the Partnership. Such services include acquisition and
management of equipment. For acquisition services, EFG was compensated by an
amount equal to 2.23% of Equipment Base Price paid by the Partnership. For
management services, EFG is compensated by an amount equal to 5% of gross
operating lease rental revenue and 2% of gross full payout lease rental revenue
received by the Partnership. Both acquisition and management fees are subject to
certain limitations defined in the Management Agreement.

   Administrative charges represent amounts owed to EFG, pursuant to Section
9.4(c) of the Restated Agreement, as amended, for persons employed by EFG who
are engaged in providing administrative services to the Partnership.
Reimbursable operating expenses due to third parties represent costs paid by EFG
on behalf of the Partnership which are reimbursed to EFG at actual cost.

   All equipment was purchased from EFG, one of its affiliates, including other
equipment leasing programs sponsored by EFG, or from third-party sellers. The
Partnership's acquisition cost was determined by the method described in Note 2
to the financial statements included in Item 14, herein.

   All rents and proceeds from the sale of equipment are paid directly EFG. EFG
temporarily deposits collected funds in a separate interest-bearing escrow
account prior to remittance to the Partnership. At December 31, 1999, the
Partnership was owed $22,736 by EFG for such funds and the interest thereon.
These funds were remitted to the Partnership in January 2000.

   Certain affiliates of the General Partner own Units in the Partnership as
follows:

         -----------------------------------------------------------------
                                                         Percent of Total
                                            Number of      Outstanding
                    Affiliate              Units Owned        Units
         -----------------------------------------------------------------

         Atlantic Acquisition Limited
         Partnership                         11,442           3.99%
         -----------------------------------------------------------------

         Old North Capital Limited
         Partnership                            990           0.35%
         -----------------------------------------------------------------


                                       10
<PAGE>

   Atlantic Acquisition Limited Partnership ("AALP") and Old North Capital
Limited Partnership ("ONC") are both Massachusetts limited partnerships formed
in 1995 and affiliates of EFG. The general partners of AALP and ONC are
controlled by Gary D. Engle. In addition, the limited partnership interests of
ONC are owned by Semele. Gary D. Engle is Chairman and CEO of Semele.

   (b) Certain Business Relationships

   None.

   (c) Indebtedness of Management to the Partnership

   None.

   (d) Transactions with Promoters

   See Item 13(a) above.


                                       11
<PAGE>

PART IV

Item 14. Exhibits, Financial Statement Schedules and Reports on Form 8-K.

(a) Documents filed as part of this report:

   (1)   Financial Statements:

         Report of Independent Auditors........................................*

         Statement of Financial Position
         at December 31, 1999 and 1998.........................................*

         Statement of Operations
         for the years ended December 31, 1999, 1998 and 1997..................*

         Statement of Changes in Partners' Capital
         for the years ended December 31, 1999, 1998 and 1997..................*

         Statement of Cash Flows
         for the years ended December 31, 1999, 1998 and 1997..................*

         Notes to the Financial Statements.....................................*

   (2)   Financial Statement Schedules:

         None Required.

   (3)   Exhibits:

         Except as set forth below, all Exhibits to Form 10-K, as set forth in
         Item 601 of Regulation S-K, are not applicable.

         A list of exhibits filed or incorporated by reference is as follows:

Exhibit
Number
------

  2.1    Plaintiffs' and Defendants' Joint Motion to Modify Order Preliminarily
         Approving Settlement, Conditionally Certifying Settlement Class and
         Providing for Notice of, and Hearing on, the Proposed Settlement was
         filed in the Registrant's Annual Report on Form 10-K/A for the year
         ended December 31, 1998 as Exhibit 2.1 and is incorporated herein by
         reference.

  2.2    Plaintiffs' and Defendants' Joint Memorandum in Support of Joint Motion
         to Modify Order Preliminarily Approving Settlement, Conditionally
         Certifying Settlement Class and Providing for Notice of, and Hearing
         on, the Proposed Settlement was filed in the Registrant's Annual Report
         on Form 10-K/A for the year ended December 31, 1998 as Exhibit 2.2 and
         is incorporated herein by reference.


        *Incorporated herein by reference to the appropriate portion of the
         1999 Annual Report to security holders for the year ended December 31,
         1999 (see Part II).


                                       12
<PAGE>

Exhibit
Number
------

  2.3     Order Preliminarily Approving Settlement, Conditionally Certifying
          Settlement Class and Providing for Notice of, and Hearing on, the
          Proposed Settlement (August 20, 1998) was filed in the Registrant's
          Annual Report on Form 10-K/A for the year ended December 31, 1998 as
          Exhibit 2.3 and is incorporated herein by reference.

  2.4     Modified Order Preliminarily Approving Settlement, Conditionally
          Certifying Settlement Class and Providing for Notice of, and Hearing
          on, the Proposed Settlement (March 22, 1999) was filed in the
          Registrant's Annual Report on Form 10-K/A for the year ended December
          31, 1998 as Exhibit 2.4 and is incorporated herein by reference.

  2.5     Plaintiffs' and Defendants' Joint Memorandum in Support of Joint
          Motion to Further Modify Order Preliminarily Approving Settlement,
          Conditionally Certifying Settlement Class and Providing for Notice of,
          and Hearing on, the Proposed Settlement is filed in the Registrant's
          Annual Report on Form 10-K for the year ended December 31, 1999 as
          Exhibit 2.5 and is included herein.

  2.6     Second Modified Order Preliminarily Approving Settlement,
          Conditionally Certifying Settlement Class and Providing for Notice of,
          and Hearing on, the Proposed Settlement (March 5, 2000) is filed in
          the Registrant's Annual Report on Form 10-K for the year ended
          December 31, 1999 as Exhibit 2.6 and is included herein.

  4       Amended and Restated Agreement and Certificate of Limited Partnership
          included as Exhibit A to the Prospectus, which is included in
          Registration Statement on Form S-1 (No. 33-35148).

  10.1    Promissory Note in the principal amount of $1,310,000 dated March 8,
          2000 between the Registrant, as lender, and Echelon Residential
          Holdings LLC, as borrower, is filed in the Registrant's Annual Report
          on Form 10-K for the year ended December 31, 1999 as Exhibit 10.1 and
          is included herein.

  10.2    Pledge Agreement dated March 8, 2000 between Echelon Residential
          Holdings LLC (Pledgor) and American Income Partners V-A Limited
          Partnership, as Agent for itself and the Registrant, is filed in the
          Registrant's Annual Report on Form 10-K for the year ended December
          31, 1999 as Exhibit 10.2 and is included herein.

  13      The 1999 Annual Report to security holders, a copy of which is
          furnished for the information of the Securities and Exchange
          Commission. Such Report, except for those portions thereof which are
          incorporated herein by reference, is not deemed "filed" with the
          Commission.

  23      Consent of Independent Auditors.

  99(a)   Lease agreement with Horizon Air Industries, Inc. was filed in the
          Registrant's Annual Report on Form 10-K for the year ended December
          31, 1991 as Exhibit 28 (a) and is incorporated herein by reference.

  99(b)   Lease agreement with General Motors Corporation was filed in the
          Registrant's Annual Report on Form 10-K for the year ended December
          31, 1995 as Exhibit 99 (d) and is incorporated herein by reference.


                                       13
<PAGE>

  99(c)   Lease agreement with Awin Leasing Company, Inc. was filed in the
          Registrant's Annual Report on Form 10-K for the year ended December
          31, 1997 as Exhibit 99 (e) and is incorporated herein by reference.

  99(d)   Lease agreement with Enseco Incorporated was filed in the Registrant's
          Annual Report on Form 10-K for the year ended December 31, 1998 as
          Exhibit 99 (e) and is incorporated herein by reference.

  99(e)   Lease agreement with Quanterra Incorporated is filed in the
          Registrant's Annual Report on Form 10-K for the year ended December
          31, 1999 Exhibit 99 (e) and is included herein.

(b) Reports on Form 8-K

    None.


                                       14
<PAGE>

                                   SIGNATURES

   Pursuant to the requirements of the Securities Exchange Act of 1934, this
report has been signed below on behalf of the registrant and in the capacity and
on the date indicated.


          AMERICAN INCOME FUND I-B, a Massachusetts Limited Partnership


                       By: AFG Leasing VI Incorporated,
                       a Massachusetts corporation and the
                       General Partner of the Registrant.


By: /s/ Geoffrey A. MacDonald               By: /s/ Gary D. Engle
   -------------------------------             ---------------------------------
Geoffrey A. MacDonald                       Gary D. Engle
Chairman and a member of the                President and Chief Executive
Executive Committee of EFG and              Officer and a member of the
President and a Director of the             Executive Committee of EFG
General Partner                             (Principal Executive Officer)


Date:     March 30, 2000                    Date:     March 30, 2000
     -----------------------------               -------------------------------


By: /s/ Gary M. Romano                      By: /s/ Michael J. Butterfield
   -------------------------------             ---------------------------------
Gary M. Romano                              Michael J. Butterfield
Executive Vice President and Chief          Senior Vice President, Finance and
Operating Officer of EFG and Clerk          Treasurer of EFG and Treasurer
of the General Partner                      of the General Partner
(Principal Financial Officer)               (Principal Accounting Officer)


Date:     March 30, 2000                    Date:     March 30, 2000
     -----------------------------               -------------------------------


                                       16
<PAGE>

                                  EXHIBIT INDEX
                                 1999 Form 10-K

Exhibit

2.5     Plaintiffs' and Defendants' Joint Memorandum in Support of
        Joint - Motion to Further Modify Order Preliminarily Approving
        Settlement, Conditionally Certifying Settlement Class and
        Providing for Notice of, and Hearing on, the Proposed
        Settlement.

2.6     Second Modified Order Preliminarily Approving Settlement,
        Conditionally Certifying Settlement Class and Providing for
        Notice of, and Hearing on, the Proposed Settlement (March 5,
        2000).

10.1    Promissory Note in the principal amount of $1,310,000 dated
        March 8, 2000 between the Registrant, as lender, and Echelon
        Residential Holdings LLC, as borrower.

10.2    Pledge Agreement dated March 8, 2000 between Echelon
        Residential Holdings LLC (Pledgor) and American Income
        Partners V-A Limited Partnership, as Agent for itself and the
        Registrant.

99(e)   Lease agreement with Quanterra Incorporated.


                                       17